It is common for hearing impaired persons to use portable amplifier devices that can be hooked on and supported by the ear, and more particularly behind the auricle, with a semi-flexible pipe extending into the acoustic meatus. These devices amplify the sounds so as to allow the hearing impaired person to more clearly hear surrounding sounds. Howver, when the hearing disability is acute, or when the person is completely deaf, these amplifier devices may not be sufficient or may be entirely useless.
People with this acute hearing disability or complete deafness communicate via a sign language and via reading the movement of the lips of the person transmitting information. Even when the hearing disability is not extremely important, reading the lips of the interlocutor is computer practice, and can be used concurrently with the hearing aid device, to help understand the sometimes less understandable pronunciation of a speaker person. When the speaker does not have free access to use its hands during conversation, especially teachers having to manipulate board chalks, notes for their courses or other devices, the reading of the lips takes a particular importance, since sign language cannot be relied upon.
However, for the lip reading to be readily accomplished, the teacher must always face its class students. Moreover, the number of students is then limited, because of the maximum distance from the teacher which can be tolerated, for lip reading by a student located far away from the teacher will be significantly hampered, if not completely impossible. Also, a teacher facing a particular portion of the class students would do so to the detriment of others. Finally, the teacher may not readily use the blackboard usually located at the front end of the class, behind the teacher, while simultaneously talking, for the teacher would then be turning his back to the class students, who could not see his lips and therefore could not accomplish the lip reading.
In an era where most types of professions are accessible to the hearing impaired or deaf persons, it is possible also that the teacher be called upon to manipulate machinery, work on wood components, or work in many other fields requiring hand held equipment, in which sign language is difficult, if not impossible, during the equipment operation, and in which lip reading can be difficult, depending on the equipment used.
U.S. Pat. No. 5,886,735 issued in 1999 to E. T. Bullister shows a headset including a head-engaging frame supporting a camera which, directly or through a reflecting mirror, will film the facial area of the person wearing the headset. The headset can be provided with a microphone. The person wearing the headset is thus able to transmit both his image and his speech through computerised means, for allowing videoconferencing. The subject matter disclosed in the Bullister patent is especially oriented towards the question of the correction of the distortion of the image obtained by the camera, since the camera is positioned in a closely adjacent fashion relative to the face of the person wearing the headset.
One problem with the system disclosed in the Bullister patent is that the image transmission does not occur in real time. According to the person skilled in the art of the present invention, real time is defined as a maximum delay of 33 msec (milliseconds) between the moment when the image is perceived and the moment when the sound is perceived (c.f. “The Effect of Imperfect Cues on the Reception of Cued Speech”, written by Maroula Sarah Bratakos of the Massachusetts Institute of Technology, September 1995). In the Bullister patent, software image correction occurs, while is time-consuming, i.e. at least about 500 msec for a full image. Furthermore, signal compression through a MPEG compressor takes place, which delays the image transfer of approximately 33 msec, as does the decompression through a MPEG decompressor, the latter not being shown in the Bullister patent, but being necessary to decompress the image compressed by the MPEG compressor. Thus, important delays amounting to up to 2000% and more of a real time transmission, occur with the device shown in the Bullister patent.
This relatively important time delay in the transmission of the images during video-conferencing, is not a problem with the system of the Bullister patent, since there is no need for precise real time transmission of the image in video-conferencing technology. Indeed, since the sound transferred through the computerised means can be synchronised with the image, the videoconferencing participants will not notice any time delay between the sound and the image being transferred. A 100 to 600 msec delay can occur without hampering significantly the video-conference. However, this important time delay can and does become an important problem in the field of the present invention.
Another problem associated with the system of the Bullister patent, is that it uses phone lines to transmit its information, using a modem. Again, this is not a problem in the field of video-conferencing, but is a problem in the field of the present invention. Indeed, the cumbersome computer, with wires and casings, it not adapted for high mobility purposes in which freedom of movement is required.
Yet another problem associated with the device shown in the Bullister patent, is that it includes an image correction device. The Bullister patent shows this device as either a distortion correction software, which is time consuming as detailed hereinabove; or a mirror or a lense which will both diminish the quantity of light received by the camera, and thus the image will be obscured.
International patent application filed under number PCT/JP85/00398 and published under number WO 86/01060 on Feb. 13, 1986—inventor Hiroshi ONO—discloses a data transmitting device using a telephone. FIG. 6 of the Ono patent application shows an embodiment of this invention in which a teacher uses the system according to the Ono application, for the benefit of hearing-impaired students in a class. Indeed, the teacher is equipped with a headset carrying a camera filming the teacher's lips, and transmitting this information to a screen provided on the hearing impaired student's desk to allow the student to accomplish lip-reading on the screen when he cannot directly view the teacher's lips.
An important problem with the system according to the Ono application, is that a telephone data transmission occurs. Indeed, the heart of the Ono application relies on the data phone-type transmission, including wires linking the camera headset to the end visualising screens. This is very undesirable, for three reasons:    1) the telephone system shown in the Ono application is heavy and cumbersome;    2) the wires linking all the elements are also very cumbersome, especially since they limit the movements of the teacher, who may become entangled in his wires; and    3) use of the phone lines restricts the quantity of information that can be sent to the screens; for example, conventional phone lines are limited to frequencies which are not higher than 3500 Hz, with the consequence that high-frequency syllables or letters, for example the letters “s”, “f” and “th”, become very difficult to hear and differentiate from one another. This is to be compared to the 20 Hz minimum to 20,000 Hz maximum range of frequency of sounds for which the normal person can be sensitive with his ears.